ON THE HYPOTHESIS OF EVOLUTION. 149 



lute ignorance ; including the development of one important mode 

 of its expression — speech ; as well as that of the moral qualities, 

 and of man's social system — the form in which his ideas of moral- 

 ity are first displayed. 



The expression '* evolution of morality" need not offend, for 

 the question in regard to the laws of this evolution is the really 

 important part of the discussion, and it is to the opposing views 

 on this point that the most serious interest attaches. 



a. Development of Intelligence, 



If the brain is the organ of mind, we may be surprised to find 

 that the brain of the intelligent man scarcely differs in structure 

 from that of the ape. Whence, then, the difference of power? 

 Though no one will now deny that many of the Mammalia are 

 capable of reasoning upon observed facts, yet how greatly the re- 

 sults of this capacity differ in number and importance from those 

 achieved by human intelligence ! Like water at the temperatures 

 of 50° and 53°, where we perceive no difference in essential char- 

 acter, so between the brains of the lower and higher monkeys no 

 difference of function or of intelligence is perceptible. But what 

 a difference do the two degrees of temperature from 33° to 31° 

 produce in water ! In like manner the difference between the 

 brain of the higher ape and that of man is accompanied by a dif- 

 ference in function and power, on which man's earthly destiny 

 depends. In development, as with the water, so with the higher 

 ape ; some Rubicon has been crossed, some floodgate has been 

 opened, which marks one of Nature's great transitions, such as 

 have been called ** expression-points" of progress. 



What point of progress in such a history would account for 

 this accession of the powers of the human intelligence ? It has 

 been answered, with considerable confidence — the power of speech. 

 Let us picture man without speech. Each generation would learn 

 nothing from its predecessors. Whatever originality or observa- 

 tion might yield to a man would die with him. Each intellectual 

 life would begin where every other life began, and would end at a 

 point only differing with its original capacity. Concert of action, 

 by which man's power over the material world is maintained, 

 would not exceed, if it equaled, that which is seen among the 

 bees ; and the material results of his labors would not extend be- 

 yond securing the means of life and the employment of the sim- 

 plest modes of defense and attack. 



